professional development programme coastal infrastructure … · nearshore breakwater structure...

The University of the West Indies Organization of

American States

PROFESSIONAL DEVELOPMENT PROGRAMME:

COASTAL INFRASTRUCTURE DESIGN, CONSTRUCTION AND MAINTENANCE

A COURSE IN

COASTAL DEFENSE SYSTEMS I

CHAPTER 11

STRUCTURAL DESIGN

By DAVE BASCO, PhD Professor, Department of Civil and Environmental Engineering

And Director, the Coastal Engineering Centre, Old Dominion University

Norfolk, VA

Organized by Department of Civil Engineering, The University of the West Indies, in conjunction with Old Dominion University, Norfolk, VA, USA and Coastal Engineering Research Centre, US Army, Corps of Engineers, Vicksburg, MS, USA.

St. Lucia, West Indies, July 18-21, 2001

STRUCTURAL DESIGN OFSTRUCTURAL DESIGN OF

David R. Basco, Ph.D, P.E.Director, The Coastal Engineering Center Old Dominion University,Norfolk, Virginia

USA 23529 [email protected]

COURSE ORGANIZATIONCOURSE ORGANIZATION• Course 2.1: Design of Coastal Structures I

- Stability of loose-material structures (breakwaters and revetments)

- Case studies: Introduction, Example Problems VI-7

• Course 2.2: Design of Coastal Structures II- Design philosophy; probabilistic design methods- Role of damage in coastal structure design- Cross-sectional design (breakwaters/revetments)- Balanced design prinicples- Case study

• Course 4: Design of Marine Structures- Seawalls and bulkheads- Beaches- Example problems VI-7 Armor Layer Stability

Coastal Engineering Practice CommitteeCEM Preview

Steven A. Hughes. Ph.D., P.E.Coastal and Hydraulics Laboratory

US Army Engineer Research and Development Center

David R. Basco. Ph.D., P.E.Coastal Engineering Center

Old Dominion University


Overview of Armor Layer StabilityRubble-Mound Trunk and Head StabilityRiprap and Toe StabilityCross-Section DesignExample Problems

CEM Chapter VI-5-3 (Author: Hans F. Burcharth)CEM Chapter VI-7 (Author: David R. Basco)

Based on:


Movement of armor units• Rocking• Displacement from layer• Sliding of layer• Settlement of layer

Not armor unit breakage


Parameter Stability Equation


Sea State Variables• Wave height• Wave length• Wave steepness• Wave angle• Wave Asymmetry• Spectrum shape• Water depth• Water density

Structure Variables• Armor layer slope• Freeboard• Armor density• Armor gradation• Armor weight• Armor shape• Packing density• Layer thickness• Porosity of layers


Classified by:• Type of armor unit• Water depth• Superstructure• Dynamic• Crest elevation

• Non-overtopped• Low-crested• Submerged

• Based on small-scale physical models• Testing of designs is recommended• Always test unusual designs

Model Testing




Based on:


Design Guidance for These Situations

Hudson’s Equation


where




Based on:


Gradation Range:

with


Design guidance for:• Sloping trunk and head• Vertical trunk and head

Toe berms…• Support main armor layer• Prevent damage by scour




Based on:


One Side Exposed to Waves


Both Sides Exposed to Waves


Geometric Design Aspects• Crest elevation and width• Concrete cap• Armor layer thickness• Primary layer bottom elevation• Toe berm• Structure head• Lee-side armor• Underlayers• Bedding/filter layer• Scour protection

Preliminary Design Phases

1. Structure geometry2. Evaluate construction

technique3. Evaluate design materials


Crest width:

Armor layer thickness:

Riprap layer thickness:

(whichever is greatest)




Based on:

� Revetment StructureSame as runup and overtopping exmplThe CBBT Island Case Study

� Nearshore Breakwater StructureChesapeake Bay –Bay Ridge,MDCape Henry-Fort Story,VA

� Jetty Structure Oregon Inlet,NC

• Impermeable Revetment• Non-overtopping Waves• Armor Stone

CBBT original design

• October 31,1991 Northeaster• The Great “Halloween Storm” of 1991• The Perfect Storm (Junger,1997)• The Storm of the Century (movie)

• The design wave height• The evolution of design waves• Impermeable revetments• Non-overtopping waves

• Table VI-6-4 Hudson formula• Table VI-6-5 Van der Meer (plunging)• Table VI-6-6 Van der Meer (surging)

• (a)Damage Curve Relations for VI-7-10• (b)Damage Curve Relations for VI-7-11

• Nearshore breakwaters• Permeable• Submerged

SUMMARY: ARMORSUMMARY: ARMOR--LAYER STABILITYLAYER STABILITY

1. Hudson (1974) SPM (1984)1. Hudson (1974) SPM (1984)•• Limited applicabilityLimited applicability

-- ONLY permeable structuresONLY permeable structures-- ONLY nonONLY non--overtopping wave conditionsovertopping wave conditions

•• Factors not consideredFactors not considered-- Wave period, Wave period, TTpp

-- Variable structure permeability, PVariable structure permeability, P-- Damage level, SDamage level, S-- Storm duration (number of waves), tStorm duration (number of waves), tdd

SUMMARY: ARMORSUMMARY: ARMOR--LAYER STABILITYLAYER STABILITY

2. CEM (2000)2. CEM (2000)•• No limitationsNo limitations

-- Includes wave overtopping and Includes wave overtopping and submerged submerged condtionscondtions

-- Includes Includes TTpp, P, S and t, P, S and tdd factorsfactors•• Methods easy for EXCELMethods easy for EXCEL•• Includes partial safety factors for designIncludes partial safety factors for design

Use CEM (2000) methods to estimate armorUse CEM (2000) methods to estimate armor--layer stability.layer stability.

professional development programme coastal infrastructure … · nearshore breakwater structure...

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